At present, HCFC refrigerants such as R22 utilized in air conditioners have environmental issues to destroy the ozone layer.
In recent years, it is proposed to use HFC refrigerants as alternative refrigerants of HCFC refrigerants, but HFC refrigerants have environmental issues to facilitate the global warming.
Therefore, it has been studied to use HC refrigerants which do not destroy the ozone layer and do not facilitate the global warming.
However, since HC refrigerants are flammable, if the refrigerants leak, there is a danger of explosion or firing, and it is necessary to ensure the safety.
Conventionally, it is proposed to light a warning lamp if the leakage of refrigerants is detected as disclosed in Japanese Patent Applications Laid-open No. H3-2113972 and No. H6-180166.
However, the conventional measures have a problem that since the leakage of refrigerant occurs very unusually, even if the user is informed of the leakage of refrigerant, the user does not know how to deal with the leakage and will be at a loss.
Thereupon, the present invention has been accomplished to solve the conventional problem, and it is an object of the invention, in the case of the leakage of a dangerous refrigerant such as flammable refrigerant, to inform a user of the danger and measures to deal with it.